There have been a number of centrifugal casting devices. Such devices employ centrifugal force to cause molten metal to be forced into small crevices in a mold. The present invention is directed towards a portable centrifugal casting machine which may be used for the casting of small metallic objects.
The basic operation of a centrifugal casting machine is well known, such as disclosed in U.S. Pat. No. Re. 17,783, issued to Gardner, et al, on Aug. 26, 1930. A casting arm is pivotably mounted at a centrally balanced point, ordinarily achieved by having a balance weight placed at one end of the casting arm. An extension arm is pivotably mounted to the casting arm so that it can rotate in a horizontal plane only. The extension arm supports the crucible and flask which contains the mold of the item to be cast. The crucible has an aperture in one end which aligns with the aperture of the mold entrance. Metal is deposited in the crucible and then melted by a heat source such as a blow torch. The extension arm supporting the crucible and flask assembly is placed in a position tangential to the direction of rotation of the casting arm to assist the centrifugal force in driving the molten metal into the mold. The casting arm is then rotated forcing the molten metal into the mold. The extension arm continues to automatically adjust so as always to maintain the molten metal under a centrifugal force. The molten metal is forced into the mold where it cools forming the casting. The prior art devices, however, did not provide an effective shield which could be easily attached to a portable centrifugal castor, in order to completely prevent the possible spillage of the molten metal during the casting operation. It was also essential that the shield not interfere in any manner with the actual ability to operate the casting device. In Gardner, U.S. Pat. No. Re. 17,783, a vertical shield 35 was provided as part of the stop. This shield, however, would not be effective to completely prevent possible spillage of the molten metal during casting.
The prior art devices also did not have a simple and inexpensive means for rotating the casting arm. The centrifugal casting device had internal springs or were motor driven. This is an undesirable feature which reduces the portable nature of the device and its ease of operation. In the present invention, an improved portable centrifugal casting machine is provided which has a shield which prevents the possible spillage of the molten metal during operation and which may be readily operated with safety and accuracy.